In the field of printing, the most common type printer has been the printer which impacts against record media that is caused to be moved past a printing line or line of printing. As is well-known, the impact printing operation depends upon the movement of impact members, such as print hammers or wires or the like, which are typically moved by means of an electromechanical drive system and which system enables precise control of the impact members.
In the field of dot matrix printers, it has been quite common to provide a print head which has included therein a plurality of print wire actuators or solenoids arranged or grouped in a manner to drive the respective print wires a very short, precise distance from a rest or non-printing position to an impact or printing position. The print wires are generally either secured to or engaged by the solenoid plunger or armature which is caused to be moved such precise distance when the solenoid coil is energized and wherein the plunger or armature normally operates against the action of a return spring.
It has also been quite common to provide an arrangement or grouping of such solenoids in a circular configuration to take advantage of reduced space available in the manner of locating the print wires in that specific area between the solenoids and the front tip of the print head adjacent the record media. In this respect, the actuating ends of the print wires are positioned in accordance with the circular arrangement and the operating or working ends of the print wires are closely spaced in vertically-aligned manner adjacent the record media. The availability of narrow or compact actuators permits a narrower or smaller print head to be used and thereby reduces the width of the printer because of the reduced clearance at the ends of the print line. The print head can also be made shorter because the narrow actuators can be placed in side-by-side manner closer to the record media for a given amount of wire curvature.
In the wire matrix printer which is utilized for receipt and for journal printing operations, the print head structure may be a multiple element type and may be horizontally disposed with the wire elements aligned in a vertical line and supported on a print head carriage which is caused to be moved or driven in a horizontal direction for printing in line manner across the receipt or journal paper and wherein the drive elements or transducers may be positioned in a circular configuration with the respective wires leading to the front tip of the print head. In the wire matrix printer which is utilized for business forms or like record media printing operation, the print head may be oriented in a manner wherein the nose is pointed downward for printing on the form, slip or like record media while the carriage and print head are moved above and across the form or like record media in the horizontal direction.
Further, in the wire matrix printer which is utilized for receipt, slip and journal printing operations, the individual print heads may be vertically oriented and printing performed by means of the print wires moving downwardly to impact on the record media. Alternatively, the individual print heads may be horizontally oriented and printing performed by means of the print wires moving horizontally to impact on the record media. A preferred number of four of such individual print heads is common in known arrangements.
The dot matrix printer is commonly used in an electronic cash register (ECR) or in a point of sale (POS) terminal. A stamp device also is commonly used in dot matrix printing and may comprise ink impregnated material such as porous rubber contained in a holder. The holder may be coupled to a solenoid or like actuator to press the stamp device against record media suitably placed against a platen or like supporting member or stand.
In such conventional stamping devices, the face of the stamp may not always be straight or square with the surface of the supporting member and which may result in uneven printing. The conventional stamping device may be constructed in a manner such that the angle of the stamping face varies to conform to the slope of the supporting member during the course of the printing operation.
Representative documentation in the field of stamp apparatus includes U.S. Pat. No. 806,111, issued to F. DeCoppet on Dec. 5, 1905, which discloses a stamping device having spaced conical collars with one collar traversed by one end of a spiral spring.
U.S. Pat. No. 2,541,800, issued to J. E. Whittaker on Feb. 13, 1951, discloses a shiftable stamp holder wherein a swivel head which carries a marking stamp will adjust itself automatically to suit the angle. The head is formed with a semi-spherical cavity and a compression spring presses against a washer on a shank of the holder.
U.S. Pat. No. 2,887,043, issued to P. V. Terry on May 19, 1959, discloses a self-aligned platen which uses a ball and socket to automatically position the platen to uniformly press a tape against selected printed characters.